package com.zlink.springcloud.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @author:Clarence
 * @date 2022/2/24 17:00
 * @motto Practice is the sole criterion for testing truth.
 * 自定义实现轮询算法
 */
@Component
public class MyLB implements LoadBalancer{


    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncreament(){
        //自旋锁实现
        int current;
        int next;
        do{
            current = this.atomicInteger.get();
            next = current >= 2147483647 ? 0 : current + 1;
        }while (!this.atomicInteger.compareAndSet(current,next));
        System.out.println("*********第几次访问，次数next:"+next);
        return next;
    }

    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncreament() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
